Services & DistributionQuestion 12 of 521
What is the general rule for the metal water piping system inside a building served by an electrical service?
a.It must be left isolated from the grounding system
b.It may only be grounded through a water heater
c.It must be used as the sole grounding electrode
d.It must be bonded, sized per Table 250.102(C)(1)
Explanation
Per 250.104(A), interior metal water piping must be bonded to the service grounded conductor/enclosure or GEC, with the bonding jumper sized from Table 250.102(C)(1). Isolation is prohibited, and water pipe alone cannot be the sole electrode.
Law Reference: 2023 NEC §250.104(A)Practice all 521 questions free — no signup required.
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